Siemens Sinumerik 840D sl Function Manual page 589

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When service is required (motor defective or encoder defective), it might be
necessary to completely replace the motor or just the motor encoder.
In this case, the motor encoder must be re--calibrated. This influences the behavior
of Safety Integrated if the functionality "safe limit positions" or "safe cams" have
been activated for the axis in question, i.e. the axis has the status "safely refer-
enced". Depending on which motor measuring system is used, it might be
necessary to select a different procedure.
The procedure for replacing a motor with absolute value encoder and to replace a
motor with incremental encoder are described in the following text. The end of the
Chapter discusses 2--encoder systems and encoder modules.
Boundary conditions
As mentioned above, the functionality "safe limit positions" or "safe cams" is active
for the axis in question.
The user agreement is set for the axis. This means that the axis has had the status
"safely referenced" at least once -- the actual position value of the NC and the SI
actual values (axis/drive) have been appropriately calibrated/aligned.
"Safe limit positions" or "Safe cams" have been able to be used.
A motor or motor encoder has to be replaced under these general conditions.
Replacing a motor with absolute value encoder
In order to set--up the encoder, the offset between the machine zero and the zero
of the absolute encoder was determined.
The calibrated state is identified by the control using
MD34210 ENC_REFP_STATE = 2.
The important factor when replacing a motor (also without Safety Integrated) is that
a defined position reference can be established with respect to the mechanical
parts of the machine. For example, by mounting and removing the motor at a
defined mechanical position or appropriately re--calibrating the system after the
motor has been replaced.
After the old motor has been removed and the new motor installed, another actual
position value is read by the new absolute value encoder (there is no longer a
defined reference to the correctly calibrated actual position value).
Therefore the following error profile appears when the control boots:
Alarm 27001
values: NCK x, drive y.
The comparison between the saved stop position and the actual position indicates
a larger deviation than specified in MD36944 $MA_SAFE_REFP_POS_TOL or
parameter p9544 "SI Motion actual value comparison tolerance (referencing)"
The alarm results in a STOP B followed by a STOP A (safe pulse cancellation) for
the axis involved.
© Siemens AG 2015 All Rights Reserved
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) - - 10.2015 Edition
Axis <name of the axis> fault in a monitoring channel, Code 1003,
Commissioning
9.6 Replacing a motor or encoder
9-589